* Electron Configuration: Chlorine has 17 electrons, with the electron configuration of 2-8-7. This means it has 7 electrons in its outermost shell (valence shell).

* Octet Rule: Atoms tend to gain or lose electrons to achieve a stable configuration of 8 electrons in their outer shell (the octet rule).

* Ion Formation: To achieve a stable octet, chlorine will gain one electron, making its electron configuration 2-8-8. This gives it a negative charge, forming the chloride ion (Cl⁻).